ABSTRACT Residence time distribution (RTD) affected lethal effects of heat on 1.27 cm diameter pa... more ABSTRACT Residence time distribution (RTD) affected lethal effects of heat on 1.27 cm diameter particles in the holding section of an aseptic processing system. The variations in particle center and particle surface F0 were determined as a function of particle density, flow rate, and particle to fluid heat transfer coefficient, hfp. Particles with density ratios of 1.00-1.04 relative to the carrier fluid showed diverse RTD characteristics in the hold tube. Particles with density ratio of 1.01 had the least residence time. The distribution of the particle center F0 value increased with increase in the hfp.
ABSTRACT ABSTRACTA method applying photo-sensors was developed to determine particle residence ti... more ABSTRACT ABSTRACTA method applying photo-sensors was developed to determine particle residence time distributions in the holding tube of aseptic processing systems. Multiple sensor pairs installed around a transparent glass tube (50.8 mm, i.d.) created a two-dimensional “optical-grid” for detecting particle movement. Detection of spherical particles (polystyrene, 19.1 mm diameter) could be achieved at particle velocities below 2.67 m/s to comply with sensor response time. A normal distribution of particle residence times was obtained from 75 replicated runs. The laminar flow assumption for the fastest fluid element was found to be conservative for public safety concerns in solid-liquid two-phase systems using the single particle basis for sizing holding sections.
ABSTRACT Residence times were studied for single particles (polystyrene spheres 19.1 mm diam) in ... more ABSTRACT Residence times were studied for single particles (polystyrene spheres 19.1 mm diam) in the straight portion of the holding section of a continuous flow system. Particle residence times were all less than the mean residence time of fluid; their ranges were within particle-to-fluid residence time ratios of 0.8 to 1.0. The velocities of the fastest moving particles were all about 1.25 times the mean fluid velocity in the turbulent flow regime. Particle density was important in the flow patterns of two-phase flow. The effect of particle-to-fluid density ratios on the particle residence time followed a quadratic function where particles with density ratio of 1.01 had the least residence time.
ABSTRACT Residence time distribution (RTD) affected lethal effects of heat on 1.27 cm diameter pa... more ABSTRACT Residence time distribution (RTD) affected lethal effects of heat on 1.27 cm diameter particles in the holding section of an aseptic processing system. The variations in particle center and particle surface F0 were determined as a function of particle density, flow rate, and particle to fluid heat transfer coefficient, hfp. Particles with density ratios of 1.00-1.04 relative to the carrier fluid showed diverse RTD characteristics in the hold tube. Particles with density ratio of 1.01 had the least residence time. The distribution of the particle center F0 value increased with increase in the hfp.
ABSTRACT ABSTRACTA method applying photo-sensors was developed to determine particle residence ti... more ABSTRACT ABSTRACTA method applying photo-sensors was developed to determine particle residence time distributions in the holding tube of aseptic processing systems. Multiple sensor pairs installed around a transparent glass tube (50.8 mm, i.d.) created a two-dimensional “optical-grid” for detecting particle movement. Detection of spherical particles (polystyrene, 19.1 mm diameter) could be achieved at particle velocities below 2.67 m/s to comply with sensor response time. A normal distribution of particle residence times was obtained from 75 replicated runs. The laminar flow assumption for the fastest fluid element was found to be conservative for public safety concerns in solid-liquid two-phase systems using the single particle basis for sizing holding sections.
ABSTRACT Residence times were studied for single particles (polystyrene spheres 19.1 mm diam) in ... more ABSTRACT Residence times were studied for single particles (polystyrene spheres 19.1 mm diam) in the straight portion of the holding section of a continuous flow system. Particle residence times were all less than the mean residence time of fluid; their ranges were within particle-to-fluid residence time ratios of 0.8 to 1.0. The velocities of the fastest moving particles were all about 1.25 times the mean fluid velocity in the turbulent flow regime. Particle density was important in the flow patterns of two-phase flow. The effect of particle-to-fluid density ratios on the particle residence time followed a quadratic function where particles with density ratio of 1.01 had the least residence time.
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